Light emitting element, light emitting device, and electronic apparatus

ABSTRACT

An organic EL element includes a pixel electrode, a light emitting function layer that is formed on the pixel electrode, an electron injection layer formed on the light emitting function layer, and a counter electrode that is formed on the electron injection layer and that has semi-transmissive reflectivity, in which the counter electrode contains a reductive material that reduces material of the electron injection layer and Ag with atomic ratio of 75% or more, and an adsorption layer is formed on the counter electrode.

This application is a continuation application of U.S. patentapplication Ser. No. 15/951,338, filed Apr. 12, 2018, which is adivisional application of U.S. patent application Ser. No. 15/452,089filed Mar. 7, 2017, which claims the benefit of Japanese PatentApplication No. 2016-063257 filed Mar. 28, 2016. The disclosure of theprior applications is hereby incorporated by reference herein in theirentirety.

BACKGROUND 1. Technical Field

The present invention relates to a light emitting element, a lightemitting device, and an electronic apparatus.

2. Related Art

Since it is possible for an organic EL element as a light emittingelement to be miniaturized or thinned in comparison to a light emittingdiode (LED), application has been observed of a micro display such as ahead mounted display (HMD) or an electronic view finder (EVF). In such amicro display, in order to improve brightness, a configuration issuggested in which a main component of an electrode (second electrode)on a side to which light is extracted is Ag (for example, refer toJapanese Patent No. 5411469).

Meanwhile, when the second electrode that has Ag as a main component isused, there is a concern that concavities and convexities are generatedin the second electrode due to aggregation of Ag atoms, and the secondelectrode is damaged due to stress being applied to the concavities andconvexities according to a load from an inorganic compound film that isformed on an upper layer. Therefore, a configuration is suggested inwhich a stress mitigation layer is disposed between the second electrodethat has Ag as the main component and the inorganic compound film inorder to mitigate stress to the second electrode (for example, refer toJapanese Patent No. 5613998).

However, when moisture or oxygen that is present within the lightemitting device infiltrates the second electrode since Ag is extremelyrich in reactivity, Ag contained in the second electrode reacts withmoisture or oxygen. For example, when moisture or oxygen infiltrates thesecond electrode from an outer periphery portion of the pixel andspreads up to a light emission region, a light emission area of theorganic EL element becomes small due to the Ag reaction, and as aresult, leads to reduction of brightness. Such temporal reduction ofbrightness tends to occur since the more compact and high-definition thelight emitting device, the more moisture or oxygen tends to spread up tothe light emission region. That is, when content of Ag contained in thesecond electrode is high in order to improve brightness of the organicEL element, there is a problem in that there is a concern that influencetends to be received due to reaction of Ag with moisture or oxygen andleads to deterioration of a light emission characteristic andreliability quality reduction in light emission life.

SUMMARY

The invention can be realized in the following aspects or applicationexamples.

Application Example 1

According to this application example, there is provided a lightemitting element including a first electrode, a light emitting functionlayer that is formed on the first electrode, an electron injection layerformed on the light emitting function layer, and a second electrode thatis formed on the electron injection layer and that has semi-transmissivereflectivity, in which the second electrode contains a reductivematerial that reduces material of the electron injection layer and Agwith atomic ratio of 75% or more, and an adsorption layer is formed onthe second electrode.

According to the configuration of the light emitting element of theapplication example, electron injection is improved while lightextraction efficiency is improved since the second electrode contains Agwith atomic ratio of 75% or more. Then, deterioration of power supplyperformance by reducing film quality due to aggregation of Ag atoms issuppressed since the second electrode contains the reductive material inaddition to Ag. Accordingly, in the second electrode, both improvementof optical characteristics as a semi-transmissive reflective film inwhich brightness is improved and an improvement of electricalcharacteristics as an electrode are possible. In addition, it ispossible to suppress infiltration of moisture or oxygen to the secondelectrode that contains Ag by adsorbing moisture or oxygen thatinfiltrates from outside of the light emitting element in the adsorptionlayer formed on the second electrode. As a result, it is possible toimprove brightness and reliability quality of the light emittingelement.

Application Example 2

In the light emitting element according to the application example, itis preferable that a material of the adsorption layer be the samematerial as the reductive material.

According to the configuration of the application example, it ispossible to configure the light emitting element of less material.

Application Example 3

In the light emitting element according to the application example, itis preferable that the material of the adsorption layer be Mg or Al.

According to the configuration of the application example, it ispossible to effectively suppress infiltration of moisture or oxygen fromoutside to the second electrode in the adsorption layer since thematerial of the adsorption layer is Mg or Al that tends to react withmoisture or oxygen. In addition, it is possible to suppress aggregationof Ag atoms by containing Mg or Al in the second electrode as thereductive material.

Application Example 4

In the light emitting element according to the application example, itis preferable that a light absorption rate of the adsorption layer be30% or less.

According to the configuration of the application example, it ispossible to suppress light extraction efficiency reduction to be smalldue to providing the adsorption layer by setting the light absorptionrate of the adsorption layer to 30% or less.

Application Example 5

In the light emitting element according to the application example, itis preferable that a thickness of the adsorption layer be 1 nm or more.

According to the configuration of the application example, it ispossible to more reliably suppress infiltration of moisture or oxygenfrom outside of the light emitting element to the second electrode dueto the thickness of the adsorption layer being 1 nm or more.

Application Example 6

In the light emitting element according to the application example, itis preferable that the thickness of the adsorption layer be thinner thana thickness of the second electrode.

According to the configuration of the application example, it ispossible to suppress light extraction efficiency reduction to be smallwhile suppressing moisture or oxygen that infiltrates from outside ofthe light emitting element from reaching the second electrode by settingthe thickness of the adsorption layer to be thinner than the thicknessof the second electrode.

Application Example 7

In the light emitting element according to the application example, itis preferable that Ag which is contained in the second electrode haveatomic ratio of 98% or less.

Although it is possible to improve brightness of the light emittingelement as the amount of Ag contained in the second electrode is great,power supply performance deteriorates due to film quality being reducedwhen content of Ag is too great. According to the configuration of theapplication example, it is possible to improve optical characteristicsin a range in which electrical characteristics of the second electrodeis not deteriorated since Ag that is contained in the second electrodehas atomic ratio of 98% or less.

Application Example 8

According to this application example, there is provided a lightemitting device, in which the light emitting element described above isprovided in each pixel and a sealing layer is provided that is formed tocover the light emitting element.

According to the configuration of the light emitting device of theapplication example, it is possible to provide the light emitting devicewhich is bright and has superior reliability quality since infiltrationof moisture or oxygen from outside to the light emitting element issuppressed by the sealing layer.

Application Example 9

In the light emitting device according to the application example, it ispreferable that the sealing layer include a first sealing layer, aflattening layer made from an organic material that is laminated on thefirst sealing layer, and a second sealing layer that is laminated on theflattening layer.

According to the configuration of the application example, it ispossible to more reliably suppress infiltration of moisture or oxygenfrom outside since there is a configuration in which the sealing layerhas three layers including the flattening layer. Note that, even in theunlikely event of a case where cracks are generated in the first sealinglayer and moisture or oxygen that is contained in the flattening layerinfiltrates up to the light emitting element, it is possible to suppressmoisture or oxygen from reaching the second electrode using theadsorption layer.

Application Example 10

In the light emitting device according to the application example,arrangement pitch of the pixels may be 10 μm or less.

In a high-definition light emitting device with a pixel arrangementpitch of 10 μm or less, the light emission region in each pixel is smallin comparison to a light emitting device in which the pixel arrangementpitch is larger. Therefore, when moisture or oxygen infiltrates andreacts with Ag of the second electrode, a phenomenon tends to occur inwhich an area of a part that substantially emits light within the lightemission region is small and is darkened. According to the configurationof the application example, it is possible to provide the light emittingdevice which is bright and has superior reliability quality even in ahigh-definition light emitting device with a pixel arrangement pitch of10 μm or less since it is possible to suppress infiltration of moistureor oxygen from outside to the second electrode using the sealing layerand the adsorption layer.

Application Example 11

According to this application example, there is provided an electronicapparatus including the light emitting device described in theapplication examples above.

According to the configuration of the application example, it ispossible to provide the electronic apparatus that has superior displayquality and reliability quality.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic planar view illustrating a configuration of anorganic EL apparatus according to a first embodiment.

FIG. 2 is a equivalent circuit schematic illustrating an electricalconfiguration of the organic EL apparatus according to the firstembodiment.

FIG. 3 is a schematic planar view illustrating an arrangement of organicEL elements in sub pixels.

FIG. 4 is a schematic sectional view illustrating a structure of theorganic EL element along line IV-IV in FIG. 3.

FIG. 5 is an enlarged sectional view illustrating a structure of theorganic EL element according to the first embodiment.

FIG. 6 is a table illustrating a configuration and test results ofexamples and comparative examples.

FIG. 7 is a diagram which describes a measurement method of a lightabsorption rate using an adsorption layer.

FIG. 8 is a graph illustrating a relationship between a thickness and alight absorption rate of the adsorption layer.

FIG. 9 is a schematic view illustrating a configuration of a headmounted display as an electronic apparatus according to a secondembodiment.

FIG. 10 is an enlarged sectional view illustrating a structure of theorganic EL element according to a comparative example.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments which embody the invention will be described below withreference to the drawings. Note that, the drawings which are used aredisplayed by appropriately enlarging and shrinking such that the portionwhich is described is in a recognizable state.

Note that, in the embodiments below, for example, a case where “on asubstrate” is described, if there is no specific description, disposingso as to come into contact on the substrate, a case of disposing on thesubstrate via another construction, a case of disposing a portion so asto come into contact on the substrate, or a case where a portion isdisposed via another component are included.

First Embodiment

Light Emitting Device

First, an organic EL apparatus is described with reference to FIGS. 1 to3 as a light emitting device according to a first embodiment. FIG. 1 isa schematic planar view illustrating a configuration of the organic ELapparatus according to the first embodiment. FIG. 2 is a equivalentcircuit schematic illustrating an electrical configuration of theorganic EL apparatus according to the first embodiment. FIG. 3 is aschematic planar view illustrating an arrangement of organic EL elementsin sub pixels. An organic EL apparatus 100 according to the embodimentis a suitable self-luminous micro display in a display portion of a headmounted display (HMD) described above.

Light Emitting Device Structure

As shown in FIG. 1, the organic EL apparatus 100 as the light emittingdevice according to the embodiment has an element substrate 10 and aprotective substrate 40. Both substrates are adhered disposed opposite afiller 42 (refer to FIG. 4).

The element substrate 10 has a display region E and a non-display regionF that surrounds the display region E. A sub pixel 18B that generatesblue (B) light, a sub pixel 18G that generates green (G) light, and asub pixel 18R that generates red (R) light are arranged in the displayregion E, for example, in a matrix shape. The organic EL apparatus 100is provided with a full color display in which a pixel 19 that includesthe sub pixel 18B, the sub pixel 18G, and the sub pixel 18R is thedisplay unit.

Note that, in the description below, the sub pixel 18B, the sub pixel18G, and the sub pixel 18R may be collectively referred to as sub pixel18. The display region E is a region in which light that is generatedfrom the sub pixel 18 is transmitted and contributes to display. Thenon-display region F is a region in which light that is generated fromthe sub pixel 18 is not transmitted and does not contribute to display.

The element substrate 10 is larger than the protective substrate 40, anda plurality of external connection terminals 103 are arranged along afirst side of the element substrate 10 that protrudes from theprotective substrate 40. A data line driving circuit 15 is providedbetween the plurality external connection terminals 103 and the displayregion E. A scanning line driving circuit 16 is provided between othersecond side and third side which face each other orthogonal to the firstside, and the display region E.

The protective substrate 40 is smaller than the element substrate 10,and is disposed such that the external connection terminals 103 areexposed. The protective substrate 40 is a substrate with lighttransmissivity, and for example, is able to use a quartz substrate, aglass substrate, or the like. In the display region E, the protectivesubstrate 40 has a role such that an organic EL element 30 (refer toFIG. 2) disposed in sub pixel 18 described above is not damaged, and isdisposed so as to face at least the display region E. A top emissionsystem is adopted in the organic EL apparatus 100 of the embodiment inwhich light that is generated from sub pixel 18 is extracted from theprotective substrate 40 side.

In the description below, the direction along the one side section alongwhich the external connection terminals 103 are arranged is described asan X direction, and the direction along the other two side sections(second side and third side) which face each other orthogonal to the oneside section is described as a Y direction. The direction from theelement substrate 10 toward the protective substrate 40 is a Zdirection. In addition, a view from the protective substrate 40 sidealong the Z direction is referred to as “planar view”.

In the embodiment, in the display region E, sub pixels 18 that obtainlight emission of the same color are arranged in a column direction (Ydirection), sub pixels 18 that obtain light emission of different colorsare arranged in a row direction (X direction), and an arrangement of subpixels 18 of a so-called stripe method is adopted. The sub pixel 18 hasthe organic EL element 30 and a color filter 36 (refer to FIG. 3 or FIG.4). A detailed configuration of the organic EL element 30 and the colorfilter 36 will be described.

Note that, in FIG. 1, arrangement of the sub pixels 18B, 18G, and 18R inthe display region E is indicated, but the arrangement of the sub pixels18 in the row direction (X direction) is not particularly limited to theorder of B, G, R. For example, the order may be G, B, R. In addition,arrangement of the sub pixels 18 is not limited to the stripe method,may be a delta method, a Bayer method, and an S stripe method, andadditionally, the shape and size of the sub pixels 18B, 18G, and 18R arenot limited to being the same.

Light Emitting Device Electrical Configuration

As shown in FIG. 2, the organic EL apparatus 100 has scanning lines 12,data lines 13, and power supply lines 14 which intersect with eachother. The scanning lines 12 are electrically connected to the scanningline driving circuit 16, and the data lines 13 are electricallyconnected to the data line driving circuit 15. In addition, the subpixels 18 are provided in the region that is partitioned by the scanninglines 12 and the data lines 13.

The sub pixel 18 has the organic EL element 30 as the light emittingelement, and the pixel circuit 20 which controls driving of the organicEL element 30. Hereinafter, the organic EL element 30 that is disposedon the sub pixel 18B is referred to as an organic EL element 30B, theorganic EL element 30 that is disposed on the sub pixel 18G is referredto as an organic EL element 30G, and the organic EL element 30 that isdisposed on the sub pixel 18R is referred to as an organic EL element30R.

The organic EL element 30 includes a pixel electrode 31 as the firstelectrode, a light emitting function layer 32, an electron injectionlayer 33, and a counter electrode 35 as the second electrode. The pixelelectrode 31 functions as a positive electrode that injects a positivehole in the light emitting function layer 32. The counter electrode 35functions as a negative electrode that injects electrons in the lightemitting function layer 32. The electron injection layer 33 is a layerthat has a function of increasing electron injection efficiency from thecounter electrode 35 to the light emitting function layer 32.

In the light emitting function layer 32, an exciton (an exciton or astate in which the positive hole and the electron are tethered to eachother using Coulomb force) is formed using the injected positive holeand electrons, and a part of energy is released as fluorescence orphosphorescence when the exciton is extinguished (when the positive holeand the electrons are recombined). In the embodiment, the light emittingfunction layer 32 is configured to obtain white emitted light from thelight emitting function layer 32.

The pixel circuit 20 includes a switching transistor 21, a storagecapacitor 22, and a driving transistor 23. Two transistors 21 and 23 areable to be configured using, for example, an n channel type or a pchannel type transistor.

A gate of the switching transistor 21 is electrically connected to thescanning lines 12. A source of the switching transistor 21 iselectrically connected to the data lines 13. A drain of the switchingtransistor 21 is electrically connected to the gate of the drivingtransistor 23.

The drain of the driving transistor 23 is electrically connected to thepixel electrode 31 of the organic EL element 30. A source of the drivingtransistor 23 is electrically connected to the power supply lines 14.The storage capacitor 22 is electrically connected between the gate ofthe driving transistor 23 and the power supply lines 14.

When the scanning lines 12 are driven and the switching transistor 21 isswitched to an ON state using a control signal that is supplied from thescanning line driving circuit 16, potential is held in the storagecapacitor 22 via the switching transistor 21 based on an image signalthat is supplied from the data line 13. The ON and OFF state of thedriving transistor 23 is determined according to a potential of thestorage capacitor 22, that is, a gate potential of the drivingtransistor 23. Then, when the driving transistor 23 is switched to theON state, current of an amount according to the gate potential flowsfrom the power supply line 14 to the organic EL element 30 via thedriving transistor 23. The organic EL element 30 emits light atluminance according to the amount of current that flows to the lightemitting function layer 32.

Note that, a configuration of the pixel circuit 20 is not limited tohaving two transistors 21 and 23, and for example, may be furtherprovided with a transistor for controlling current that flows in theorganic EL element 30.

Light Emitting Element Arrangement in Sub Pixel

Next, the arrangement of the organic EL element 30 and the color filter36 in the sub pixel 18 will be described with reference to FIG. 3.

As shown in FIG. 3, the pixel electrode 31 of the respective organic ELelements 30 is disposed on the plurality of sub pixels 18 that arearranged in a matrix shape in the X direction and the Y direction. Indetail, the pixel electrode 31B of the organic EL element 30B isarranged on the sub pixel 18B, the pixel electrode 31G of the organic ELelement 30G is arranged on the sub pixel 18G, and the pixel electrode31R of the organic EL element 30R is arranged on the sub pixel 18R. Therespective pixel electrodes 31 (31B, 31G, 31R) are formed in asubstantially rectangular shape in planar view, and a longitudinaldirection is disposed along the Y direction.

The organic EL apparatus 100 has a configuration in which three subpixels 18B, 18G, and 18R arranged in the X direction are displayed asone pixel 19. The arrangement pitch of the sub pixels 18B, 18G, and 18Rin the X direction is, for example, 10 μm or less. Accordingly, theorganic EL apparatus 100 is a high-definition light emitting device.

An insulation film 28 is formed to cover an outer edge of each pixelelectrode 31B, 31G, and 31R. In planar view, opening portions 28KB,28KG, and 28KR with substantially a rectangular shape are formed on thepixel electrodes 31B, 31G, and 31R on the insulation film 28. Within theopening portions 28KB, 28KG, and 28KR, the respective pixel electrodes31B, 31G, and 31R are exposed. Note that, the shape of the openingportions 28KB, 28KG, and 28KR is not limited to a substantialrectangular shape, and may be a track shape in which, for example, ashort side is an arc shape.

In the sub pixels 18B, 18G, and 18R, a region in which the openingportions 28KB, 28KG, and 28KR are provided is a light emission region EMin which the organic EL elements 30B, 30G, and 30R emit light. In thesub pixels 18B, 18G, and 18R, a region in which the insulation film 28is provided is a light emission suppression region S in which lightemission of the organic EL elements 30B, 30G, and 30R is suppressed.Accordingly, in the sub pixels 18B, 18G, and 18R, the periphery of thelight emission region EM is the light emission suppression region S.

The color filter 36 is disposed on the sub pixels 18B, 18G, and 18R. Thecolor filter 36 is configured by a blue (B) colored layer 36B, a green(G) colored layer 36G, and a red (R) colored layer 36R. In detail, thecolored layer 36B is disposed with respect to the plurality of subpixels 18B that are arranged in the Y direction, the colored layer 36Gis disposed with respect to the plurality of sub pixels 18G, and thecolored layer 36R is disposed with respect to the plurality of subpixels 18R.

That is, the colored layer 36B is arranged in the stripe shape extendingin the Y direction so as to overlap with the pixel electrodes 31B(opening portion 28KB) that are arranged in the Y direction. The coloredlayer 36G is arranged in the stripe shape extending in the Y directionso as to overlap with the pixel electrodes 31G (opening portion 28KG)that are arranged in the Y direction. Similarly, the colored layer 36Ris arranged in the stripe shape extending in the Y direction so as tooverlap with the pixel electrodes 31R (opening portion 28KB) that arearranged in the Y direction.

Light Emitting Element Structure

Next, the structure of the organic EL element 30 will be described asthe light emitting element with reference to FIG. 4. FIG. 4 is aschematic sectional view illustrating the structure of the organic ELelement along line IV-IV in FIG. 3.

As shown in FIG. 4, the organic EL apparatus 100 has the elementsubstrate 10 and the protective substrate 40 that are disposed facingvia the filler 42. The filler 42 has a role of adhering the elementsubstrate 10 and the protective substrate 40, and is configured by, forexample, epoxy resin, an acrylic resin, or the like that havetransmissivity.

The element substrate 10 is provided with the organic EL element 30, andthe sealing layer 34 and the color filter 36 that are laminated on theorganic EL element 30. The organic EL element 30 is provided with a basematerial 11 as a substrate in the invention, and a light reflectionlayer 25, a light transmitting layer 26, the pixel electrode 31 as thefirst electrode, the light emitting function layer 32, the electroninjection layer 33, the counter electrode 35 as the second electrode,and the adsorption layer 37 are laminated in order in the Z direction onthe base material 11.

For example, the base material 11 is a semiconductor substrate ofsilicon and the like. As described above, the scanning lines 12, thedata lines 13, power supply lines 14, the data line driving circuit 15,the scanning line driving circuit 16, a pixel circuit 20 (switchingtransistor 21, storage capacitor 22, and driving transistor 23), and thelike are formed on the base material 11 using a known technology (referto FIG. 2). In FIG. 4, illustration of a wiring or a circuitconfiguration is omitted.

Note that, the base material 11 is not limited to a semiconductorsubstrate such as silicon, and may be, for example, a substrate such asquartz or glass. In other words, a transistor that configures the pixelcircuit 20 may be a MOS type transistor that has an active layer in thesemiconductor substrate, and may be a thin film transistor or a fieldeffect transistor that is formed on the substrate such as quartz orglass.

The light reflection layer 25 is disposed to extend over the sub pixels18B, 18G, and 18R, and light that is emitted from the organic ELelements 30B, 30G, and 30R of each sub pixel 18B, 18G, and 18R isreflected. As the formation material of the light reflection layer 25,it is preferable to use, for example, aluminum (Al), silver (Ag), andthe like that is able to realize high reflectance in a visible lightregion.

The light transmitting layer 26 is provided on the light reflectionlayer 25. The light transmitting layer 26 is configured by a firstinsulation film 26 a, a second insulation film 26 b, and a thirdinsulation film 26 c. The first insulation film 26 a is disposed toextend over the sub pixels 18B, 18G, and 18R on the light reflectionlayer 25. The second insulation film 26 b is laminated on the firstinsulation film 26 a and is disposed to extend over the sub pixel 18Gand the sub pixel 18R. The third insulation film 26 c is laminated onthe second insulation film 26 b and is disposed on the sub pixel 18R.

That is, the light transmitting layer 26 of the sub pixel 18B isconfigured by the first insulation film 26 a, the light transmittinglayer 26 of the sub pixel 18G is configured by the first insulation film26 a and the second insulation film 26 b, and the light transmittinglayer 26 of the sub pixel 18R is configured by the first insulation film26 a, the second insulation film 26 b, and the third insulation film 26c. Accordingly, the thickness of the light transmitting layer 26 becomeslarger in order of the sub pixel 18B, the sub pixel 18G, and the subpixel 18R. A transparent material in a visible light range of, forexample, silicon oxide, silicon nitride, titanium oxide, and the like isused in the first insulation film 26 a, the second insulation film 26 b,and the third insulation film 26 c.

The pixel electrode 31 is provided on the light transmitting layer 26.For example, the pixel electrode 31 is configured from a transparentconductive film such as an indium tin oxide (ITO) film or the like, andis formed in an island shape in each sub pixel 18. The insulation film28 is disposed to cover the peripheral edge portion of each pixelelectrode 31B, 31G, and 31R. As described above, the opening portion28KB is formed on the pixel electrode 31B, the opening portion 28KG isformed on the pixel electrode 31G, and the opening portion 28KR isformed on the pixel electrode 31R on the insulation film 28. Theinsulation film 28 is made from, for example, silicon oxide.

In a part in which the opening portions 28KB, 28KG, and 28KR areprovided, the pixel electrodes 31 (31B, 31G, 31R) and the light emittingfunction layer 32 are connected, the positive hole is supplied from thepixel electrode 31 to the light emitting function layer 32, and thelight emitting function layer 32 emits light. In the region in which theinsulation film 28 is provided, supply of the positive hole from thepixel electrode 31 to the light emitting function layer 32 issuppressed, and light emission of the light emitting function layer 32is suppressed. That is, as described above, in the sub pixels 18B, 18G,and 18R, the region in which the opening portions 28KB, 28KG, and 28KRare provided is the light emission region EM, and the region in whichthe insulation film 28 is provided is the light emission suppressionregion S.

The light emitting function layer 32 is disposed to cover the wholeregion of the display region E (refer to FIG. 1) that extends over thesub pixels 18B, 18G, and 18R. The light emitting function layer 32 has,for example, a positive hole injection layer, a positive hole transportlayer, an organic light emitting layer, an electron transport layer, andthe like laminated in that order in the Z direction. The organic lightemitting layer emits light of a wavelength range from blue to red. Theorganic light emitting layer may be formed of a single layer, forexample, includes a blue light emitting layer, a green light emittinglayer, and a red light emitting layer, and may be configured by aplurality of layers that include the blue light emitting layer and ayellow light emitting layer that obtains light emission that includesthe wavelength range of red (R) and green (G).

The electron injection layer 33 is disposed to cover the light emittingfunction layer 32. The electron injection layer 33 improves electroninjection efficiency from the counter electrode 35 to the light emittingfunction layer 32, and functions to emit light of the light emittingfunction layer 32 at low voltage. It is desirable that a potentialbarrier between the counter electrode 35 and the light emitting functionlayer 32 in the negative electrode is small in order to improve electroninjection efficiency to the light emitting function layer 32. Ingeneral, as the electron injection layer 33, a halogenide (inparticular, fluoride), oxide, or the like of an element (alkali metal,alkaline earth metal, and the like) is used in which a work function islow such as LiF, Li₂O, Liq, MgO, and CaF₂. A detailed configuration ofthe electron injection layer 33 in the embodiment will be describedlater.

The counter electrode 35 is disposed to cover the electron injectionlayer 33. Since the counter electrode 35 does not function only as anelectrode and configures an optical resonator structure described belowwith the light reflection layer 25, the counter electrode 35 isconfigured to be provided with transmissivity and light reflectivity(has semi-transmissive reflectance) to serve as the semi-transmissivereflective film, and the thickness is controlled. As the main componentof the counter electrode 35, Ag which has a small light absorption ratein the visible light region is suitable. By using Ag as the maincomponent, loss (absorption) of light due to the counter electrode 35 issuppressed to be small, and it is possible to improve brightness of theorganic EL element 30.

However, Ag has a large work function and is not a reductive material.In addition, when the counter electrode 35 is configured by only Ag,deterioration of power supply performance is generated by reducing filmquality due to aggregation of Ag atoms. Therefore, it is desirable touse Ag and a reductive material in a mixture as a material of thecounter electrode 35 since electrical characteristics of the electrodeis suitable. A detailed configuration of the counter electrode 35 in theembodiment will be described later.

The adsorption layer 37 is disposed to cover the counter electrode 35.The adsorption layer 37 functions such that moisture or oxygen thatinfiltrates from outside the organic EL element 30 is adsorbed and doesnot reach up to the counter electrode 35. A material (for example, Mg orAl) that easily reacts with moisture or oxygen is used as the materialof the adsorption layer 37. A detailed configuration of the adsorptionlayer 37 in the embodiment will also be described later.

Note that, influence of the light transmitting layer 26 that hasdifferent thicknesses provided on a lower layer is received andconcavities and convexities are generated on a front surface of theorganic EL element 30 (adsorption layer 37). In more detail, in a partthat overlaps with the light emission region EM within the openingportions 28KB, 28KG, and 28KR in planar view, since the thickness of thelight transmitting layer 26 is substantially uniform, the front surfaceof the organic EL element 30 (adsorption layer 37) is substantiallyflat. Meanwhile, in a part that overlaps with the light emissionsuppression region S in which the insulation film 28 on the periphery ofthe light emission region EM is disposed in planar view, a step isgenerated due to the thicknesses of the light transmitting layer 26being different.

The sealing layer 34 is disposed to cover the organic EL element 30(adsorption layer 37). The sealing layer 34 is configured by a firstsealing layer 34 a, a flattening layer 34 b, and a second sealing layer34 c are laminated in order in the Z direction. The first sealing layer34 a and the second sealing layer 34 c are a passivation film that has abarrier property with respect to moisture or oxygen, and are formedusing an inorganic material. A material through which moisture, oxygen,or the like tend not pass, for example, silicon oxide, silicon nitride,silicon oxynitride, aluminum oxide, and the like are used as theinorganic material.

A vacuum disposition method, an ion plating method, a sputtering method,a CVD method, and the like are given as a method for forming the firstsealing layer 34 a and the second sealing layer 34 c. In the point oftending to impart damage such as heat to the organic EL element 30, itis desirable to adopt the vacuum disposition method or the ion platingmethod. The thickness of the first sealing layer 34 a and the secondsealing layer 34 c is, for example, approximately 50 nm to 1000 nm andis preferably approximately 200 nm to 400 nm such that cracks and thelike tend to occur during film formation and transmittance is obtained.

The flattening layer 34 b is formed laminated on the first sealing layer34 a to cover the organic EL element 30 (adsorption layer 37).Concavities and convexities on the front surface of the organic ELelement 30 that are generated by receiving influence of the lighttransmitting layer 26 that has different thicknesses is reflected on thefront surface of the first sealing layer 34 a. In addition, in the lightemission suppression region S in which the step is generated on thefront surface of the organic EL element 30, defects (pin holes andcracks) may be generated during film formation of the first sealinglayer 34 a.

The flattening layer 34 b mitigates concavities and convexities on thefront surface of the first sealing layer 34 a, covers defects (pin holesand cracks), foreign matter, or the like during film formation of thefirst sealing layer 34 a, and forms a substantially flat surface. Inorder to mitigate concavities and convexities on the front surface ofthe first sealing layer 34 a, it is preferable to form the flatteninglayer 34 b at a thickness of, for example, approximately 1 μm to 5 μm.Due to this, influence of the concavities and convexities tends to bereceived by the color filter 36 that is formed on the sealing layer 34(second sealing layer 34 c).

The flattening layer 34 b has transmittance, and is able to form a resinmaterial of any of, for example, heat or ultraviolet curable epoxyresin, acrylic resin, urethane resin, and silicone resin by coating andpost-curing by dissolving in an organic solvent or liquid. Note that,the flattening layer 34 b may be formed using a coating type ofinorganic material (silicon oxide and the like).

The color filter 36 is disposed on the sealing layer 34. The colorfilter 36 is configured by the colored layers 36B, 36G, and 36R that areformed by photolithography and the like using a photosensitive resinmaterial that includes color material of blue (B), green (G), and red(R) corresponding to the sub pixels 18B, 18G, and 18R. The coloredlayers 36B, 36G, and 36R of the color filter 36 function to increasecolor purity of each color of light of blue (B), green (G), and red (R)emitted to the protective substrate 40 side due to light beingtransmitted in a peak wavelength range that is extracted from each subpixel 18 using the optical resonator structure described below.

Optical Resonator Structure

Next, the optical resonator structure that has the organic EL apparatus100 according to the embodiment will be described with reference to FIG.4. The organic EL apparatus 100 according to the embodiment has theoptical resonator structure between the light reflection layer 25 andthe counter electrode 35. In the organic EL apparatus 100, lightgenerated by the light emitting function layer 32 is repeatedlyreflected between the light reflection layer 25 and the counterelectrode 35, intensity of light of a specific resonator (opticalresonator) is amplified corresponding to an optical distance between thelight reflection layer 25 and the counter electrode 35, and each colorof light of blue (B), green (G), and red (R) is emitted from theprotective substrate 40 in the Z direction as display light.

In the embodiment, the light transmitting layer 26 has a role ofadjusting the optical distance between the light reflection layer 25 andthe counter electrode 35. As described later, the thickness of the lighttransmitting layer 26 becomes larger in order of the sub pixel 18B, thesub pixel 18G, and the sub pixel 18R. As a result, the optical distancebetween the light reflection layer 25 and the counter electrode 35becomes larger in order of the sub pixel 18B, the sub pixel 18G, and thesub pixel 18R. The optical distance is able to be represented by the sumtotal of the product of the refractive index and thickness of each layerthat is present between the light reflection layer 25 and the counterelectrode 35.

For example, in the sub pixel 18B, the thickness of the lighttransmitting layer 26 is set such that the resonant wavelength (peakwavelength where luminance is maximum) is 470 nm. In the sub pixel 18G,the thickness of the light transmitting layer 26 is set such that theresonant wavelength is 540 nm. In the sub pixel 18R, the thickness ofthe light transmitting layer 26 is set such that the resonant wavelengthis 610 nm.

As a result, blue color light (B) that has a peak wavelength of 470 nmis emitted from the sub pixel 18B, green color light (G) that has a peakwavelength of 540 nm is emitted from the sub pixel 18G, and red colorlight (R) that has a peak wavelength of 610 nm is emitted from the subpixel 18R. In other words, the organic EL apparatus 100 has an opticalresonator structure that amplifies the intensity of light of thespecific wavelength, a blue light component is extracted from whitelight emitted by the light emitting function layer 32 in the sub pixel18B, a green light component is extracted from white light emitted bythe light emitting function layer 32 in the sub pixel 18G, and a redlight component is extracted from white light emitted by the lightemitting function layer 32 in the sub pixel 18R.

Note that, in place of the light transmitting layer 26, there may be aconfiguration in which the optical distance between the light reflectionlayer 25 and the counter electrode 35 is adjusted by the thicknesses ofthe pixel electrodes 31 (31B, 31G, 31R) being different from each other.

In such sub pixels 18B, 18G, and 18R, color purity of each color isincreased by transmitting each color of light of blue (B), green (G),and red (R) emitted from the organic EL elements 30B, 30G, and 30Rthrough the colored layers 36B, 36G, and 36R of the color filter 36.

Electron Injection Layer, Counter Electrode, and Adsorption LayerDetailed Configuration

Next, the detailed configuration of the electron injection layer 33 thatis provided with the organic EL element 30 according to the embodiment,the counter electrode 35, and the adsorption layer 37 will be describedwith reference to FIG. 5. FIG. 5 is an enlarged sectional viewillustrating the structure of the organic EL element according to thefirst embodiment. FIG. 5 is a diagram in which a sectional view of FIG.4 is partially enlarged.

The electron injection layer 33 according to the embodiment indicated inFIG. 5 is formed using lithium fluoride (LiF) that is a material whichis stable in the atmosphere. In the embodiment, the counter electrode 35and adsorption layer 37 include Mg that is a reductive material thatreduces a material (Li compound) of the electron injection layer 33, thelight emitting function layer 32 emits light at a lower voltage andincreases intensity of the organic EL element 30 according to the amountof Mg contained in both. The thickness of the electron injection layer33 is, for example, approximately 1 nm.

The counter electrode 35 according to the embodiment contains Ag and Mgthat is a reductive material. Since the greater the amount of Ag that iscontained in the counter electrode 35, the smaller the loss (absorption)of light and the brighter the light, it is possible to improve opticalcharacteristics of the semi-transmissive reflective film. In addition,the greater the amount of Ag that is contained in the counter electrode35, the more it is possible to improve current injection properties ofthe counter electrode 35. In the counter electrode 35 according to theembodiment, it is preferable to contain Ag with atomic ratio of 75% ormore and contain Ag of 90% or more, and it is further preferable tocontain Ag of 95% or more.

In the embodiment, the counter electrode 35 is formed using the vacuumdisposition method of a vapor deposition method. A ratio of Ag and Mgthat is contained in the counter electrode 35 is able to be adjustedaccording to a deposition velocity ratio of Ag and Mg when the counterelectrode 35 is formed. For example, it is possible to respectively setthe ratio of Ag that is contained in the counter electrode 35 to 75%,90%, and 95% due to the deposition velocity ratio of Ag and Mg being setto 3:1, 9:1, and 20:1. When the deposition velocity ratios of Ag and Mgare set to 3:1 (Ag with atomic ratio of 75%) to 20:1 (Ag with atomicratio of 95%), the possibility of the optical characteristic and thecurrent injection properties being in a suitable state is indicated inFIGS. 2, 5, and 6 in Japanese Patent No. 5411469.

Meanwhile, when there is too much Ag contained in the counter electrode35, power supply performance deteriorates by resistivity of the counterelectrode 35 raising since film quality is reduced due to aggregation ofAg atoms in an island shape. In the embodiment, other than Ag, since Mgis contained in the counter electrode 35, it is possible to suppressreduction of the film quality due to aggregation of Ag atoms. In theembodiment, Ag contained in the counter electrode 35 has an atomic ratioof 98% or less. When the deposition velocity ratio of Ag and Mg is setto 50:1 (Ag with atomic ratio of 98%), reduction of the opticalcharacteristic (luminance) and the power supply performance is indicatedin FIGS. 4, 5, and 8 in Japanese Patent No. 5411469.

In this manner, in the embodiment, it is possible to reconcileimprovement of optical characteristics of the semi-transmissivereflective film and improvement of electrical characteristics of theelectrode in the counter electrode 35 by setting Ag contained in thecounter electrode 35 in the range of atomic ratio of 75% to 98%. Thethickness of the counter electrode 35 is, for example, approximately 15nm. Note that, the counter electrode 35 may contain an element otherthan Ag and Mg.

However, when moisture or oxygen infiltrates in the counter electrode 35with Ag as the main component, since Ag is extremely rich in reactivity,Ag contained in the counter electrode 35 reacts with the moisture oroxygen. By doing this, electron injection of the counter electrode 35 isreduced, and leads to reliability quality reduction in deterioration ofa light emission characteristic and light emission service life of theorganic EL element 30. The greater the amount of Ag that is contained inthe counter electrode 35, the greater the influence on deterioration orreliability quality reduction of the light emission characteristic.Therefore, the adsorption layer 37 is provided in order for moisture oroxygen that infiltrates from outside the organic EL element 30 to beadsorbed and not reach up to the counter electrode 35.

The adsorption layer 37 according to the embodiment is formed of Mg. Mgis a material in which moisture or oxygen tend to react, and is suitableas the material of the adsorption layer 37. The adsorption layer 37 isformed using the vacuum disposition method in the same manner as thecounter electrode 35. Since Mg is a material contained as the reductivematerial in the counter electrode 35, after Ag and Mg form a film of thecounter electrode 35 as the material, it is possible to form a film ofthe adsorption layer 37 on the counter electrode 35 with only Mg as thematerial. Accordingly, it is possible to easily carry out amanufacturing process of the organic EL element 30, and it is possibleto improve productivity of the organic EL element 30.

Here, an effect due to providing the adsorption layer 37 is described incomparison to a comparative example. FIG. 10 is an enlarged sectionalview illustrating a structure of the organic EL element according to thecomparative example. An element substrate 90 of an organic EL apparatus900 that is provided with an organic EL element 38 according to thecomparative example is indicated in FIG. 10. The organic EL element 38according to the comparative example has the same configuration otherthan a point of not being provided with the adsorption layer 37 beingdifferent with respect to the organic EL element 30 according to theembodiment.

As shown in FIG. 10, in the light emission suppression region S betweenthe light emission region EM of the sub pixel 18G and the light emissionregion EM of the sub pixel 18R, a case is assumed in which a crack 51 isgenerated caused by a step, foreign matter, or the like on the frontsurface of the organic EL element 38 in the first sealing layer 34 athat covers the organic EL element 38 (counter electrode 35). In theflattening layer 34 b that is formed by a resin material such as epoxyresin on the first sealing layer 34 a, content of moisture or oxygen isreduced due to a dehydration process or film formation and the likeunder a nitrogen atmosphere, but it is difficult for moisture or oxygento be nil.

When moisture or oxygen contained in the flattening layer 34 binfiltrates up to the counter electrode 35 through the crack 51 of thefirst sealing layer 34 a, moisture or oxygen react when Ag contained inthe counter electrode 35 infiltrates in the light emission suppressionregion S. A reaction portion 53 that is formed within the counterelectrode 35 by Ag reacting with moisture or oxygen is schematicallyindicated in FIG. 10. Since there is loss of electron injection of thecounter electrode 35 in the reaction portion 53, when the reactionportion 53 is formed within the light emission region EM, the part is adark point in which the light emitting function layer 32 does notgenerate light.

When moisture or oxygen that infiltrates in the light emissionsuppression region S spreads within the counter electrode 35, as shownin FIG. 10, the reaction portion 53 is enlarged from the light emissionsuppression region S to the light emission region EM of the sub pixel18G. By doing this, since the dark spot in which the light emittingfunction layer 32 does not emit light is formed within the lightemission region EM, in the sub pixel 18G, a phenomenon (hereinafterreferred to as a pixel shrink) in which a region in which light issubstantially emitted is smaller than within the light emission regionEM is generated and brightness of the sub pixel 18G is reduced.

In this manner, when moisture or oxygen infiltrates in the counterelectrode 35 and is spread within the counter electrode 35, brightnessof the organic EL apparatus 900 is reduced due to pixel shrink beinggenerated by enlarging the reaction portion 53. Then, when reaction ofmoisture or oxygen with Ag within the counter electrode 35 temporallyproceeds leading to reliability quality reduction of the organic ELapparatus 900.

When the organic EL apparatus 900 is a high-definition light emittingdevice with a pixel arrangement pitch of the sub pixel 18 is 10 μm orless, the light emission region EM in each sub pixel 18 and the lightemission suppression region S on the periphery thereof are small incomparison to a light emitting device with a larger arrangement pitch ofthe sub pixel 18. Therefore, since moisture or oxygen tends to spread inthe light emission region EM when infiltrating the counter electrode 35,pixel shrink tends to be generated and reduction of brightness becomesmore significant.

In contrast to this, in the organic EL apparatus 100 according to theembodiment, the adsorption layer 37 is provided on the counter electrode35. FIG. 5 schematically indicates a case of moisture or oxygen thatpasses through the crack 51 of the first sealing layer 34 a infiltratingthe organic EL element 30 in the element substrate 10 of organic ELapparatus 100. In the organic EL element 30, since the counter electrode35 is covered by the adsorption layer 37, Mg contained in the adsorptionlayer 37 reacts with moisture or oxygen, the reaction occurs that isindicated in Formula (2) or Formula (3) described later, and thereaction portion 52 is formed that is a part in which oxygen atomswithin the adsorption layer 37 are adsorbed.

That is, even if moisture or oxygen infiltrates from outside the organicEL element 30, the infiltrated moisture or oxygen is adsorbed due to thereaction with Mg using the adsorption layer 37. Accordingly, even if thecontent of Ag contained in counter electrode 35 is high, sinceinfiltration of moisture or oxygen to the counter electrode 35 issuppressed by the adsorption layer 37 and it is possible to suppressgeneration of pixel shrink, it is possible to suppress brightnessreduction or reliability quality reduction of the organic EL element 30.As a result, it is possible to provide the organic EL apparatus 100 inwhich the brightness reliability quality is superior.

Here, the crack 51 of the first sealing layer 34 a tends to be generatedin the light emission suppression region S that has a step on the frontsurface of the organic EL element 30. Therefore, when moisture or oxygenthat infiltrates within the adsorption layer 37 through the crack 51reacts with Mg, the reaction portion 52 is formed in the light emissionsuppression region S. Accordingly, in the organic EL apparatus 100 inwhich the reaction portion 52 is formed in the adsorption layer 37 asindicated in FIG. 5, concentration of oxygen atoms contained in theadsorption layer 37 in the light emission suppression region S is higherthan the concentration of oxygen atoms contained in the adsorption layer37 in the light emission region EM.

Note that, here, a case is described in which moisture or oxygencontained in the flattening layer 34 b is adsorbed more than theadsorption layer 37, but even in the unlikely event of a case wheremoisture or oxygen infiltrates from outside the sealing layer 34 (secondsealing layer 34 c), infiltration into the counter electrode 35 issuppressed since Mg contained in the adsorption layer 37 is adsorbed byreacting with infiltrated moisture or oxygen.

From the viewpoint of suppressing infiltration of moisture or oxygeninto the counter electrode 35, it is considered that thickness of theadsorption layer 37 is preferably thick. However, when thickness of theadsorption layer 37 is thickened, since light loss (light absorption)increases due to the adsorption layer 37 with respect to light that isemitted from the light emitting function layer 32, brightness that isrealized is impaired by setting the main component of the counterelectrode 35 to Ag. Therefore, a suitable range of thickness of theadsorption layer 37 (upper limit and lower limit) will be described incomparison to examples and comparative examples.

Adsorption Layer Thickness Suitable Range

FIG. 6 is a table illustrating a configuration and test results ofexamples and comparative examples. FIG. 7 is a diagram which describes ameasurement method of a light absorption rate using the adsorptionlayer. FIG. 8 is a graph illustrating a relationship between thethickness and a light absorption rate of the adsorption layer.

As shown in FIG. 6, in order to find the suitable range of thickness ofthe adsorption layer 37, two comparative examples and seven exampleswere prepared. Comparative Example 1 is different in a point of notbeing provided with the electron injection layer 33 and adsorption layer37 with respect to the organic EL element 30 according to the embodimentand thickness of the counter electrode 35 is the same as 15 nm, but Agcontained in the counter electrode 35 is approximately 9.1% (during filmformation, the deposition velocity ratio of Ag and Mg is 1:10).

Comparative Example 2 is only different in a point of not being providedwith the adsorption layer 37 with respect to the organic EL element 30according to the embodiment, and is the same in a point of beingprovided with the electron injection layer 33 with thickness of 1 nmthat is configured by two layers of LiF and Mg and the counter electrode35 with thickness of 15 nm including 90.9% of Ag (film is formed withthe deposition velocity ratio of Ag and Mg of 10:1). Accordingly,Comparative Example 2 is different from Comparative Example 1 in a pointof being provided with the electron injection layer 33 and a point ofthe ratio of Ag that is contained in the counter electrode 35 beinghigh.

A number value (set to one) that references measurement results ofluminance of Comparative Example 1 is indicated in the “RELATIVELUMINANCE” column in FIG. 6. In addition, generation time is indicatedin the “HIGH-TEMPERATURE TEST” column in FIG. 6 in a case where theorganic EL apparatus is left under an atmosphere of 60° C. for 1000hours and pixel shrink described above is generated, and “−” isindicated in a case where pixel shrink is not generated. Note that, the“HIGH-TEMPERATURE TEST” is a test in which reduction of reliability isaccelerated by moisture that infiltrates through the crack 51 of thefirst sealing layer 34 a, and for example, a test condition is setassuming a case in which an electronic apparatus is left that isprovided with the organic EL apparatus inside an automobile under theblazing sun.

Relative luminance is 1.76 in Comparative Example 2 with respect toComparative Example 1, the ratio of Ag that is contained in the counterelectrode 35 in Comparative Example 2 being high and the electroninjection layer 33 being provided is understood to contribute toimprovement of brightness. Meanwhile, pixel shrink is generated in 230hours in Comparative Example 2 with respect to pixel shrink not beinggenerated in 1000 hours in Comparative Example 1, it is understood thatpixel shrink tends to occur due to a high ratio of Ag that is containedin the counter electrode 35 reacting with moisture or oxygen.

Example 1 to Example 7 have the same configuration of the electroninjection layer 33 and the counter electrode 35 as Comparative Example2, but are different in the point of being provided with the adsorptionlayer 37. In addition, in Examples, 1, 2, 3, 4, 5, 6, and 7, thicknessof the adsorption layer 37 is set to different respective values of 0.5nm, 1 nm, 2 nm, 3 nm, 5 nm, 8 nm, and 10 nm.

Concerning relative luminance, Example 7 is lower than ComparativeExample 1 and is 0.87 with respect to Example 1, but Example 1 toExample 6 are higher values than Comparative Example 1. As a result, thethinner the thickness of the adsorption layer 37, the higher theluminance (in other words, the thicker the thickness of the adsorptionlayer 37, the lower the luminance), it is understood that it is possibleto realize higher luminance than Comparative Example 1 if thickness ofthe adsorption layer 37 is 8 nm or less.

Meanwhile, in the high-temperature test, pixel shrink is generated in450 hours in Example 1, but pixel shrink is not generated in 1000 hoursin Example 2 to Example 7. As a result, even if the ratio of Ag that iscontained in the counter electrode 35 is high, pixel shrink tends not tobe generated due to providing the adsorption layer 37, and if thicknessof the adsorption layer 37 is 1 nm or more, it is understood that afunction is realized of suppressing infiltration into the counterelectrode 35 by adsorbing moisture or oxygen.

Next, an upper limit of thickness of the adsorption layer 37 will beconsidered. In the organic EL element 30 according to the embodiment,the optical resonator structure is formed between the light reflectionlayer 25 and the counter electrode 35. Since the adsorption layer 37 isformed on the counter electrode 35 that is a semi-transmissivereflective film, there is demand to reduce light loss (light absorptionrate) with respect to light emitted from the optical resonator structureof the organic EL element 30, that is, light emitted from the counterelectrode 35 in the adsorption layer 37.

Therefore, as shown in FIG. 7, the counter electrode 35, the adsorptionlayer 37, and the first sealing layer 34 a are formed on the basematerial 11 and light loss is evaluated with respect to incident lightL. The counter electrode 35 has a thickness of 15 nm with the depositionvelocity ratio of Ag and Mg during film formation of 10:1 (content of Agis 90.9%). The adsorption layer 37 is formed of Mg, and the thickness isset the same respectively in Example 2 to Example 7. In the firstsealing layer 34 a, a silicon nitride film is formed at a thickness of500 nm using the CVD method.

A result in which light loss (light absorption rate) due to theadsorption layer 37 is measured in the configuration described above isindicated in FIG. 8. In FIG. 8, the horizontal axis is thickness (nm) ofthe adsorption layer 37 and the vertical axis is the light absorptionrate (%). The light absorption rate is changed per 1 nm in a range inwhich the wavelength of the incident light L is 400 nm to 700 nmindicated in FIG. 7 in each thickness of the adsorption layer 37, and anaverage value of the rate (reflectance) of reflected light Lr and therate (transmittance) of transmitted light Lt is subtracted from theincident light L that is set as 1 and calculated by Formula (1) below.In Formula (1) below, A is the light absorption rate, R (λ) isreflectance in a wavelength λ, and T (λ) is transmittance in thewavelength λ.

$\begin{matrix}{\mspace{79mu}{A = {\frac{1}{n}{\overset{n}{\sum\limits_{i = 1}}{\;\left\{ {1 - {R\left( \lambda_{i} \right)} - {T\left( \lambda_{i} \right)}} \right\}}}}}} & (1)\end{matrix}$

As shown in FIG. 8, the thicker the thickness of the adsorption layer37, the larger the light absorption rate (light loss) becomes. Mg thatconfigures the adsorption layer 37 may be an element with a largeabsorption amount of light (that is, extinction coefficient andabsorption coefficient). Due to the result of “RELATIVE LUMINANCE” inFIG. 6, if thickness of the adsorption layer 37 is 8 nm or less, higherluminance is obtained than Comparative Example 1, and when the thicknessof the adsorption layer 37 is 10 nm, luminance is lower than ComparativeExample 1. Accordingly, in a case where the material of the adsorptionlayer 37 is Mg, it is preferable that the upper limit of the thicknessbe 8 nm.

According to FIG. 8, the light absorption rate is approximately 32% whenthickness of the adsorption layer 37 be 8 nm. Thereby, in order toobtain luminance of Comparative Example 1 or more, it is preferable thatthe light absorption rate of the adsorption layer 37 is 30% or less.Accordingly, in a case where the material of the adsorption layer 37 isanother material, it is preferable that the upper limit of the thicknessof the adsorption layer 37 be a thickness with the light absorption rateof 30%.

Next, the lower limit of the thickness of the adsorption layer 37 willbe considered. As shown in FIG. 6, pixel shrink is generated in 230hours in Comparative Example 2 in which the adsorption layer 37 is notprovided, and pixel shrink is generated in 450 hours in ComparativeExample 1 in which the thickness of the adsorption layer 37 is 0.5 nm.Then, pixel shrink is not generated in 1000 hours in Examples 2, 3, 4,5, 6, and 7 in which the thickness of the adsorption layer 37 is 1 nm ormore. Here, as described above, a case in considered in which moistureor oxygen that is contained in the flattening layer 34 b infiltratesthrough the crack 51 of the first sealing layer 34 a.

In Comparative Example 1, as shown in FIG. 10, since moisture or oxygenthat is contained in the flattening layer 34 b infiltrates up to thecounter electrode 35 through the crack 51 of the first sealing layer 34a, it is considered that pixel shrink is generated. In addition, inExample 1, although moisture or oxygen that infiltrates from theflattening layer 34 b through the crack 51 of the first sealing layer 34a is approximately adsorbed by the adsorption layer 37, it is consideredthat pixel shrink is generated since a part infiltrates up to thecounter electrode 35. In Examples 2, 3, 4, 5, 6, and 7, it is consideredthat moisture or oxygen that infiltrates through the crack 51 isadsorbed by the adsorption layer 37 and infiltration to the counterelectrode 35 is suppressed.

Mg which configures the adsorption layer 37 is an element that tends toreact with moisture or oxygen. Here, in a case where Mg reacts withmoisture (water), a reaction occurs that is indicated by Formula (2), ina case where Mg reacts with oxygen, a reaction occurs that is indicatedby Formula (3), thereby the lower limit of thickness of the adsorptionlayer 37 is calculated as a trial by hypothesizing that moisture oroxygen is adsorbed by the adsorption layer 37.Mg+2H₂O→Mg(OH)₂+H₂  (2)2Mg+O₂→2MgO  (3)

In a case where water indicated in Formula (2) is reacted, two watermolecules (two oxygen atoms) are adsorbed by one Mg atom. In a casewhere oxygen indicated in Formula (3) is reacted, one oxygen atom isadsorbed by one Mg atom. Here, Mg atoms are adsorbed atoms, and thenumber of Mg atoms is defined as the number adsorbed atoms. Moisture(water) of 50 ppm is contained in the flattening layer 34 b. Note that,moisture that is contained in the flattening layer 34 b is approximately10 ppm in the comparative examples and examples described above, and 50ppm is a value that includes a larger margin than in reality.

A case where the flattening layer 34 b is formed by acrylic resin orepoxy resin is taken as an example, and specific gravity of theflattening layer 34 b is set as 1.2 g/cm³. When the thickness of theflattening layer 34 b is 2.5 μm, molecular weight of water is 18, andAvogadro□s constant is 6.02×10²³ mol⁻¹, it is possible to calculate theatom number of oxygen that is contained in the flattening layer 34 busing Formula (4) below.50 ppm×1.2 [g/cm³]×18/(6.02×10²³[1/mol])×2.5 [μm]=5.0×10¹⁴[1/cm²]  (4)

Next, it is possible to calculate thickness of the adsorption layer 37(Mg) in a case where the atom number of oxygen and the same number of Mgatoms that are calculated by Formula (4) are uniformly formed usingFormula (5) below when the atomic weight of Mg is 24, and the specificgravity of Mg is 1.74 g/cm³.50×10¹⁴[1/cm²]×24/1.74 [g/cm³]/(6.02×10²³[1/mol])×0.11 [nm]  (5)

As a result of Formula (5), the lower limit of the thickness of theadsorption layer 37 based on the trial calculation described above is0.11 nm. From an evaluation result of the example indicated in FIG. 6,pixel shrink is not generated at the thickness of the adsorption layer37 of 1 nm or more, but since pixel shrink is generated at the thicknessof the adsorption layer 37 of 0.5 nm, in a case where the material ofthe adsorption layer 37 is Mg, it is preferable that the lower limit ofthe thickness of the adsorption layer 37 is 1 nm. The value isapproximately 9.1 times 0.11 nm of the trial calculation describedabove.

It is considered that a difference of the thickness based on the trialcalculation described above and the thickness based on the evaluationresult of the example causes formation of a path through which moistureor oxygen is not spread locally (in a thickness direction) in ahorizontal direction within the adsorption layer 37 and thickness of theadsorption layer 37 being not uniform.

As a result, it is desirable that the number of adsorbed atoms (Mgatoms) that are contained in the adsorption layer 37 is at least 10times or more and preferably 20 times or more with respect to the numberof adsorbed atoms under the premise that thickness is 0.11 nm based onthe trail calculation described above. Accordingly, in a case where thematerial of the adsorption layer 37 is another material, it ispreferable that the lower limit of the thickness of the adsorption layer37 is a thickness in which the adsorbed atoms of ten times the number ofwater molecules or oxygen atoms that are contained in the flatteninglayer 34 b are contained, and is a thickness in which the adsorbed atomsof 20 times or more of the number of water molecules or oxygen atomsthat are contained in the flattening layer 34 b are contained.

Note that, since the material of the adsorption layer 37 in the exampledescribed above is Mg with a relatively large light absorptioncoefficient, the thickness of the adsorption layer 37 is preferably thinin a range in which a function is realized of adsorbing moisture oroxygen. In more detail, the thickness of the adsorption layer 37 isthinner than the thickness of the counter electrode 35, but it ispreferable to suppress extraction efficiency reduction of light that isemitted from the optical resonator structure of the organic EL element30 (light that is emitted from the counter electrode 35).

Second Embodiment

Electronic Apparatus

Next, an electronic apparatus according to a second embodiment will bedescribed with reference to FIG. 9. FIG. 9 is a schematic viewillustrating a configuration of a head mounted display as an electronicapparatus according to the second embodiment.

As shown in FIG. 9, a head mounted display (HMD) 1000 according to thesecond embodiment is provided with two display portions 1001 which areprovided to correspond to left and right eyes. An observer M is able tosee characters, images, and the like which are displayed on the displayportions 1001 by mounting the head mounted display 1000 on their head asglasses. For example, if an image is displayed taking into account aparallax in the left and right display portions 1001, it is alsopossible to enjoy viewing three-dimensional moving images.

The organic EL apparatus 100 according to the first embodiment ismounted on the display portions 1001. Accordingly, it is possible toprovide a small light weight head mounted display 1000 that has displayquality that is superior in viewing angle characteristics with highcolor purity, and in particular, a see-through type head mounted display1000 is suitable.

The head mounted display 1000 is not limited to a configuration in whichthere are two display portions 1001, and may be configured to beprovided with one display portion 1001 that corresponds to either leftor right.

Note that, the electronic apparatus in which the organic EL apparatus100 is mounted according to the first embodiment is not limited to thehead mounted display 1000. As the electronic apparatus in which theorganic EL apparatus 100 is mounted, for example, an electronicapparatus is given that has a display portion such as a personalcomputer or portable information terminal, a navigator, a viewer, and ahead-up display.

The embodiment described above essentially illustrates an aspect of theinvention, and is able to be arbitrarily modified and applied within therange of the invention. For example, the examples below are considered.

Modification Example 1

In the first embodiment, the material of the adsorption layer 37 that isprovided with the organic EL element 30 is Mg, but the invention is notlimited to the aspect. The material of the adsorption layer 37(reductive material that reduces the material of the electron injectionlayer 33) may be a metal other than Al. Al is superior in reduction ofan Li compound, treatment during manufacture is comparatively easy, andit is possible to easily use a vapor deposition method such asdeposition. In addition, the material of the adsorption layer 37 may bean organic material. In a case where the organic material is used in thematerial of the adsorption layer 37, it is preferable that theabsorption coefficient of light is small, and there is the organicmaterial that has a water-absorbing property. Note that, in a case wherethe organic material is used in the material of the adsorption layer 37,when the lower value of the thickness of the adsorption layer 37 is set,it may be considered that the number of adsorbed atoms that arecontained in the adsorption layer 37 is replaced with the number ofadsorbed molecules.

Modification Example 2

In the first embodiment, in the organic EL apparatus 100, light emittingpixels that are provided in the display region E is not limited to thesub pixels 18B, 18G, and 18R that correspond to light emission of blue(B), green (G), and red (R). For example, a sub pixel 18Y may beprovided that obtains light emission of yellow (Y) other than the threecolors described above. Thereby, it is possible to further increasecolor reproducibility. In addition, sub pixels 18 of two colors out ofthe three colors described above may be provided.

The entire disclosure of Japanese Patent Application No. 2016-063257,filed Mar. 28, 2016 is expressly incorporated by reference herein.

What is claimed is:
 1. A light emitting element comprising: a firstelectrode, that functions as a positive electrode; a light emittingfunction layer formed on the first electrode; a second electrode, thatfunctions as a negative electrode, formed on the light emitting functionlayer, wherein the second electrode comprises Ag with Ag having anatomic ratio of 75% or more; and a covering layer comprising Mg that isformed on, and in direct contact with, the second electrode, wherein athickness of the covering layer is thinner than a thickness of thesecond electrode, wherein an electron injection layer is formed on, andin direct contact with, the light emitting function layer, and theelectron injection layer comprises lithium.
 2. The light emittingelement according to claim 1, wherein the first electrode comprises ITO.3. The light emitting element according to claim 1, wherein a lightreflection layer is formed below the first electrode and comprises Ag.4. The light emitting element according to claim 3, wherein the lightreflection layer is in direct contact with the first electrode.
 5. Thelight emitting element according to claim 1, wherein the electroninjection layer comprises Liq.
 6. The light emitting element accordingto claim 1, wherein the electron injection layer comprises LiF.
 7. Thelight emitting element according to claim 1, wherein the thickness ofthe second electrode is approximately 15 nm.
 8. The light emittingelement according to claim 7, wherein the second electrode furthercomprises Mg.
 9. The light emitting element according to claim 8,wherein the covering layer is an adsorption layer.
 10. The lightemitting element according to claim 1, wherein the second electrodefurther comprises a reductive material.
 11. The light emitting elementaccording to claim 10, wherein the reductive material comprises Mg. 12.The light emitting element according to claim 11, wherein the coveringlayer is an adsorption layer.
 13. The light emitting element accordingto claim 1, wherein the covering layer is an adsorption layer.
 14. Thelight emitting element according to claim 13, wherein the thickness ofthe adsorption layer is 1 nm or more.
 15. The light emitting elementaccording to claim 1, wherein the second electrode further comprises Mg.16. The light emitting element according to claim 5, wherein thecovering layer is an adsorption layer.
 17. The light emitting elementaccording to claim 1, wherein the second electrode comprises Ag with anatomic ratio of 90% or more and 98% or less and also comprises Mg. 18.The light emitting element according to claim 17, wherein the coveringlayer is an adsorption layer.
 19. A light emitting element comprising: afirst electrode, that functions as a positive electrode; a lightemitting function layer formed on the first electrode; a secondelectrode, that functions as a negative electrode, formed on the lightemitting function layer, wherein the second electrode comprises Ag withAg having an atomic ratio of 90% or more and 98% or less; and a coveringlayer comprising Mg that is formed on, and in direct contact with, thesecond electrode, wherein a thickness of the covering layer is thinnerthan a thickness of the second electrode.
 20. The light emitting elementaccording to claim 19, wherein an electron injection layer is formed on,and in direct contact with, the light emitting function layer, and theelectron injection layer comprises lithium.
 21. The light emittingelement according to claim 20, wherein the electron injection layercomprises Liq.
 22. The light emitting element according to claim 20,wherein the second electrode further comprises Mg.
 23. The lightemitting element according to claim 22, wherein the covering layer is anadsorption layer.
 24. The light emitting element according to claim 23,wherein the thickness of the adsorption layer is 1 nm or more.